GL102 Lecture 6: Chapter 16- Groundwater
Document Summary
Groundwater: water in pores of soil and sediment & narrow fractures in bedrock, not under ground river. Groundwater slowly dissolves rock such as limestone, creating surface depressions: sinkholes. 4000,000 km3 of freshwater compared to 1200 km3 of river water. Soil moisture- molecular attraction on particles near surface. Water percolates down: all open spaces are filled w water: ground water. Capillary fringe extends upward from water table by surface tension in pore spaces. Upper limit of zone of saturation (pressure surface), Shape of water table is usually a subdued replica of the surface topography. Depth of water table is highly variable; vary seasonally and year to year. Water level of wells coincides with water table. Water tends to accumulate beneath high areas between stream valleys. During extended drought water table may drop enough to dry shallow wells. Uneven water tables may also result from variations in rainfall and permeability. Factors influencing the storage and movement of groundwater.
